i have a blackberry curve 8520 and basically i turn off my mobile network and now i dont know how to turn it back on because i cant press anything on my trackball but i can scroll up and down, anyway i can turn my mobile network back on?

Not sure about the 8520, but a BlackBerry will sometimes prompt to automatically restore connections under some circumstances. For example try pressing the phone button twice (once to open the phone app, and then again to dial the highlighted contact). If you are prompted. To turn on the mobile network or restore connections, press the return key. Be prepared to end the call if the phone starts dialing.